Induced-current effects on microwave backscatter

Microwave measurements have been made with a coherent radar in a wind-wave tank to determine the effect of induced current on backscatter. Perturbations were introduced into the wave structure by inducing a current in the water that flowed either with or against the wind. The effect of current on radar cross section was slight; the effect on the Doppler was much more pronounced. It was found that the wave components responsible for radar backscatter are predominantly free waves (that is, waves which travel at the dispersion velocity) rather than waves which are parasitic (or locked) to the dominant waves.